Method for dehydrogenating paraffins and olefins



Patented Nov. 7, 1950 METHOD FOR DEHYDROGENATING PARAFFINS AND OLEFINS Ike D. Hall, Baytown, Tcx., assignor, by mesne assignments, to Standard Oil Development Company, Elizabeth, N. J., a corporation oi Delaware pplication September 11, 1948, Serial No. 48,874

Claims. (Cl. 260-680) The present invention is directed to a method for dehydrogenating hydrocarbons. More particularly. the invention is directed to a process in which paramns such as isoparaflins are dehydrogenated and mono-oleiins such as normal monooleflns are also dehydrogenated and the products of both dehydrogenation eactions are recovered.

Prior to the. present invention, it has been conventional to the art to dehydrogenate normal mono-olefins in the presence of a catalyst to form the corresponding dioleilns. This process may employ a catalyst such as disclosed in U. S. 2,395,875 issued March 5, 1946, to Kearby, and U. S. 2,408,139 issued September 24, 1946, to Gutzeit. Catalysts of this nature are resistant to deactivation by steam. In the processes described in the aforementioned patents, the mono-olefinis admixed with steam and then passed into contact with a catalyst such as one including magnesium oxide, iron oxide, a promoter and stabilizer for the catalyst, or the admixture of steam and mono-olefin may be passed into contact with a catalyst composed substantially of iron oxide promoted with materials such as bismuth oxide and the like. Promoters for either of the two types of catalyst may include the alkali and alkaline earth compounds and particularl the oxides, hydroxides and carbonates. In the processes described in the aforementioned two patents, the normal mono-oleflns are substantially dehydrogenated to the corresponding diolefin whereas the parafllns, such as visobutane, are largely unaffected. Similarly, isobutylene in contact with catalysts oi the aforementioned types passes through the dehydrogenation reaction zone largely unaflected and serves merely as a diluent for the reaction.

On the other hand, isobutane-may be dehydrogenated under thermal conditions if it is mixed with steam at a relatively high temperature sutilcient to cause the reaction to proceed. For example, at a temperature in the range from about 1000 to 1300 F., isobutane may be dehydrogenated to isobutylene with a conversion of about 30% of isobutane to isobutylene and a selectivity of about 50%.

In the aforementioned dehydrogenation operations, steam is provided in large quantities as diluent for the reaction. It is necessary to heat the steam to a temperature in the range from about 1000 to about 1300 F- prior to its admixture with the normal butylene to form the feed stocks of the processes. By virtue of the fact that the steam is ordinarily heated to a temperature in the range between 1000 and 1300 F.

and by virtue of the fact that isobutylene is substantially inert insoiarv as dehydrogenation is concerned in the presence of catalysts of the aforementioned types, it is possible in accordance with .the present invention to dehydrogenate isobutane to isobutylene in admixture with the steam diluent employed for the dehydrogenation of normal butylene to butane.

The method of the present invention maybe described briefly as including the steps of forming a first feed mixture including an isoparafiln and steam and a second feed mixture comprising substantially normal mono-olefins, the first feed mixture being heated to a temperature in the range between 1000 and 1300 F. to cause dehydrogenation of the isoparaflin while the second feed mixture is heated to a temperature in the range between 900 to 1200" F. The first and second feed mixtures, 'after heating, are then admixed and passed in contact with a dehydrogenation catalyst which may be regenerated through the water-gas reaction to cause dehydrogenation of the mono-olefin, the combined products of the dehydrogenation reaction being treated in sequence with reagents selective for removal of diolefln, tertiary mono-olefin, and normal monoolefln, the latter being recycled to the process whereas the other products are removed for further use as desired. r

The invention may be described in greater detail as involving, for example, the formation of a mixture of isobutane and steam which is heated to a temperature in the range between 1000 and 1300 F., preferably to about 1250 F. Asecond stream including substantially normal butylenes is heated to a temperature in the range between 900 and 1200 F., preferably 1000 F. While heating the first stream to a temperature of the order 01 1250 the presence of steam and the high temperature level causes dehydrogenation of the isobutane to isobutylene at a conversion of about 30% and a selectivity of about 50%. The products from this dehydrogenation are admixed with the heated butylenes stream to form a third feed mixture which is passed into contact with a dehydrogenation catalyst such as a predominantly magnesium oxide catalyst containing iron oxide and promoters and stabilizers for the catalyst, or a predominantly iron oxide catalyst such as that disclosed in the aforementioned Gutzeit patent. On passing in contact with catalyst of the aforementioned type in the presence of steam, the butylenes are substantially dehydrogenated to butadiene while the isobutylene and isobutane introduced as a first feed in admixture with steam asaaaos taught in U. S. 2,401,973 issued June 11, 1946, to

W. D. Seyfried et al. and in U. S. 2,416,227 issued February 18, 1947, to -W. D. Seyfried. The temperatures to which the reaction products should be reduced should be a temperature in the range from about 500 to 600 F. For example, the temperature prevailing in the catalytic reactor contacting the feed admixture may be in the range from 1100 to 1300 F. and this temperature is suddenly reduced to a temperature of about 500 to 600 F. by contacting the products, including reacted and unreacted hydrocarbons, in sequence with oil and water as described in detail in U. 8. 2,414,817 issued January 28, 1947, to Carl E. Klieber et al. include absorption steps as taught in the aforementioned Seyfried et al. and Seyfrled patents. The quenched products are then subjected to fractional distillation in efilcient fractional distillation equipment such as those known to the art as superfractionation towers in which a fraction including substantially unreacted isoparafnns is obtained and a second fraction including substantially unsaturated materials including the isobutylene, unreacted normal butylenes, and butadiene is withdrawn. The first fraction including the substantially saturated material may be recycled to the thermal dehydrogenation step while the second fraction including the unsaturated material is subjected in sequence to contact with reagents selective for removal of butadiene, isobutylene, and normal butylenes, the isobutylene beingwithdrawn as a desirable product while the normal butylenes are returned to the operation for admixture with the product from the thermal dehydrogenation step and for formation of a. feed mixture to the catalytic dehydrogenation step.

The method of the present invention will now be described with reference to the drawing in which the single figure is a flow diagram of one mode of practicing the invention.

In the drawing II is a furnace which is designed to heat mono-olefins to a temperature in the range between 900 and 1200 F. while i2 is a steam superheater for heating steam to a temperature in the range between 1000 and 1300 F. Numeral I4 is a catalytic reactor or a plurality of catalytic reactors containing a catalyst such as described in the aforementioned Gutzeit and Kearby patents. There is routed to butylene furnace i I by line IS a stream consisting substantially of normal butylenes while to steam superheater l2 a stream of steam is introduced by line It from a suitable source of steam, not shown.

Admixed with the steam discharging into heater [2 by line I6 is a stream consisting substantially of isobutane which is introduced, from a source which will be described further, by line I I. Thus, feeding into steam superheater I2 is an admixture of steam and isobutane. This admixture may include steam and isoparafiln in a molal ratio in the range from :1 to 80:1. Under the conditions prevailing in steam heater l2 which may include a temperature in the range from 1000 to -1300 F. and preferably around 1250' F. the iso- Such quenching operations also butylene is substantially dehydrogenated to imbutylene. The normal butylenes discharge by line II, from a source which will be described further, into butylenes furnace I l where they are heated to a temperature in the range from 900 to 1200 F. and preferably 1000 F. and thence discharged therefrom lnto manifold, It to which is also fed the admixture of steam and dehydrogenated products of isobutane and unreacted isobutane from superheater l2. The admixture of butylenes and reacted and unreacted isobutane then discharge by way of line l9 into catalytic dehydrogenation reactor H which. as mentioned before, contains a catalyst for the dehydrogenation of the normal butylenes to butadiene. The feed mixture from manifold II in line I! passes downwardly over a catalyst bed, not shown, in reactor I4 and the products of the combined dehydrogenations including isobutylene and butadiene discharge from reactor I4 by line" 20 into a quenching and recovery zone 2| which is fllustratedby a rectangle. It will be understood that this quenching and recovery zone 2| will include all facilities for rapidly reducing the temperature of the reaction products and also for recovering the desirable products of the reactions and withdrawal of substantially inert fixed gases. For

purposes of understanding the invention proper- 1y, line 22 is shown as introducing a quenching and absorber oil into zone 2| and line 23 is shown for withdrawal of used absorber oil or quench oil from which the desirable products and the fixed gases have been removed. Line 24 is provided for removal of fixed gases and line 25 is shown as designating means for removing polymers and other heavy reaction products formed in superheater l2 and reaction zone It. A stream consisting substantially of hydrocarbons having 4 carbon atoms in the molecule is withdrawn from zone 2| by line 26 and discharges thereby into fractional distillation facilities 21 which are conveniently shown as a single fractionating tower. but which may include a plurality of fractional distillation towers. It is preferred that fractional distillation zone 21 will include facilities for separating a fraction from the products of the reactions consisting substantially of isobutane. The fraction consisting substantially of isobutane is removed from fractional distillation tower 21 by line I! and flows thereby to superheater l2 for admixture with steam introduced by line It. -Additional isobutane may be added to line II by opening valve 28 in line 28 connecting line I! to an extraneous source of isobutane.

There is removed from the bottom of fractionating zone 21 by line 30 a stream consisting substantially of unsaturated components including isobutylene, unreacted normal butylenes, and butadiene. This stream is discharged into a butadiene extraction zone 3| which is shown as a block in the diagram. Butadiene extraction zone 3| is designed toremove selectively the butadiene from the isobutylene and normal butylenes and may be provided with a suitable solvent for selective removal of butadiene. Such facilities have been described in the literature such as the aforementioned Seyfried et al. patent and a solvent such as ammoniacal cuprous acetate may be introduced thereby by line 32 and used solvent withdrawn therefrom by line 33. It will be understood that zone 3| will include all auxiliary facilities necessary for recovery of butadiene from the ammoniacal cuprous acetate. The butadiene is withdrawn from zone 3| by line 34 for use as a constituent of synthetic rubber which may be formed assumes by the reaction of the butadiene with styrene, for example.

The unabsorbed tertiary and normal monoolefin discharge from zone 3| by line and are divided into two portions, one portion being recycled by line l5 to the butylenes furnace ll while the other portion is withdrawn by line 38 and is further divided into two portions, one of which discharges by line 36 into a first isobutylene extraction zone 31 and the second is discharged by line 33 into a second isobutylene extraction zone 33 as will be described further.

Methods for extracting isobutylene from streams containing isobutylene in admixture with other hydrocarbons having 4 carbon atoms to the molecule have been taught in the art. For example, U. S. 2,400,440 issued May 14, 1946, to J. H. Cone describes a process in which isobutylene is absorbed selectively by contact with weak sulfuric acid. Other methods for extracting isobutylene from olefinic mixtures containing it include reaction of isobutylene with phenol in the presence of a catalyst. It is understood that isobutylene extraction zones 31 and 33 may include any well known isobutylene extraction method, but for purpose of this description, it is understood that it will include the method described in the aforesaid Cone patent. Isobutylene extraction zones 31 and 39 are shown as blocks in the diagram and are provided, respectively, with lines 40 and 4! for introduction of fresh sulfuric acid to the respective zones and lines 42 and 43, respectively, for withdrawal of used sulfuric acid therefrom.

The isobutylene discharged into zone 3! is selectively absorbed and the isobutylene recovered' from the acid as described in the aforesaid Cone patent is withdrawn by line 44 for further use such as, for example, in the production of synthetic rubber by copolymerization with a diolefin, or for alkylation or polymerization, The unabsorbed hydrocarbons including substantially normal butylenes with a small amount of isobutane and isobutylene and some normal butane discharge from zone 31 by line 45 into an ester still 45 where they are subjected to distillation to cause removal of small amounts of sulfuric acid esters contained therein, the esters being withdrawn from the system by line 41 while the substantially ester-free hydrocarbons are recovered overhead by line 48 and discharge thereby into line I 5 for recycling to the process as has been described. I

The second isobutylene-containing stream in line 38 admixes in line 49 with a stream containing isobutane, isobutylene, normal butane, and normal butylenes obtained from a convenient source such as from thermal catalytic cracking operations. This admixture in line 49 containing isobutylene from which the butadiene has been substantially removed flows into second isobutylene extraction zone 39 and has its isobutylene content substantially removed as has been described, the isobutylene being recovered from zone 33 by line 50 for further use as has been described with respect to that recovered by line 44. The unabsorbed hydrocarbons, including isoand normal butane and butylenes, are withdrawn from zone 39 b line 5| which discharges this stream to a normal butylenes concentration zone 52 in which furfural or acetone is used to remove selectively the normal butylenes from the admixture of isoand normal butane, the isoand normal butane being removed from the system by line 53 and may be recycled to the process for reintroduction thereto by line 23 while the normal butylenes are recovered by line 54 which discharges them into line It for introduction into butylenes furnace l I and catalytic reactor l4 as has been described.

The methods of concentrating normal butylenes 'from mixtures of normal and isobutane by solvent extraction with acetone or furiural are well known to the art and further mention of them need not be made here. Suflice to say that zone 52 will include extraction and recovery zones for separating the two types of hydrocarbons, and it is understood that the block indicating zone 52 will include all such auxiliar equipment. Line 55 is provided for introduction of fresh solvent to zone 52 while line 56 is shown for removal of used solvent. If it is desired to recovera stream consisting substantially of normal butylenes, this may be done by withdrawing from line 54 a butylenes stream by opening valve 51 in line 58.

. It will be seen from the foregoing process described in conjunction with the drawing that an integrated method for dehydrogenating an isoparaflln and normal mono-olefin in equipment that has been designed for dehydrogenating normal mono-olefins is provided and also that separation facilities for recovering separately diolefin, tertiary mono-olefins, and normal butylene are also provided.

As a specific example of the practice of the present invention, 940 mols of a stream containing 854 mols of isobutane, 43 mols isobutylene, and 43 mols of normal butane are admixed with an amount of steam ranging from 38,000 to 50,000 mols. This mixture is heated to a temperature of 1250 F. in a suitable furnace whereby the isobutylene is substantially dehydrogenated to isobutylene with a conversion of the order of 30% at about 50% selectivity. A stream consisting substantially of butylene and containing 2542 mols of normal butylenes, 11 mols of butadiene, 435 mols of normal butane, 273 mols of isobutylene, and mols of isobutane is heated to about 1000 F. This heated stream is then admixed with the heated stream containing isobutane and steam and the admixture thereof contacted with a catalyst such as that described in the aforesaid Kearby and Gutzeit patents. Contact with the catalyst for a suitable reaction time causes substantial dehydrogenation of the normal butylenes to butadiene such that the stream issuing from contact with the catalyst consists of approxi mately 5461 mols of which 485 mols are butadiene, 1875 mols are normal butylene, 529 mols are isobutylene, and 572 mols are isobutane, the remainder being normal butane and products of the reaction including fixed gases, hydrogen, and a small amount of polymer. The product is treated in a quenching and recovery zone to remove heat of reaction and to separate polymer and fixed gases. Recovered from the quench and recovery zone is a C4 fraction including 485 mols of butadiene, 1875 mols of normal butylene, 478 mols 01' normal butane, 526 mols of isobutylene, and 570 mols of isobutane. This C4 fraction is then subjected to fractional distillation to obtain an overhead fraction consisting of 470 mols of which 427 mols are isobutane and 43 mols are isobutylene, while a second fraction is recovered including 485 mols of butadiene, 1875 mols of normal butylenes, 478 mols of normal butane, 483 mols or isobutylene, and 143 mols of isobutane. This stream on extraction with ammoniacal cuprous acetate solution results in the separation of substantially all the butadiene from the stream containing it such that a stream consisting of 474 mols of buta diene and 7 mols of normal butylene is obtained, the unabsorbed portion including 2,983 mols of which 1868 mols are normal butylenes and 483 mols are isobutylene, the remainder being isobutane, normal butylenes, and small amount of butadiene. This stream of 2983 mols is split into two portions, one portion consisting of 1458 mols including 913 mols of normal butylenes, 236 mols of isobutylene, mols of isobutane, 234 mols of normal butane and mols of butadiene is returned to the butylene furnace for further reaction while the second portion consisting of 1525 mols of which 955 mols are normal butylene and 247 mols are isobutylene. the remainder being the difference between the total of the isobutylene and normal butylenes and that amount recycled to the butylenes dehydrognation reaction. This stream is also divided into two portions, one portion of which is extracted with weak sulfuric acid to remove selectively the isobutylene and the other portion is admixed with a feed stream consisting of isobutane, isobutylene, normal butane, and normal butylenes from an extraneous source and is also extracted for the removal of isobutylene in a second isobutylene extraction zone.

The product from the first isobutylene extraction zone afterremoval of isobutylene therefrom consists of 851 mols of which 629 mols are normal butylene, 4 mols are butadiene, 159 mols are normal butane, 11 mols are isobutylene, and 48 mols are isobutane. This stream is heated in a distillation zone toremove esters: The amount of esters is negligible and substantially all of this stream is recovered and returned to the butylenes furnace for dehydrogenation in the butylenes reactor. The second portion of the stream consisting of 524 mols distributed as follows: 326 mols of normal butylene, 2 mols of butadiene, 85 mols of normal butane, 86 mols of isobutylene, and mols of isobutane, is admixed with the extraneous C4. fraction which consists of 1215 mols of isobutane, 427 mols of isobutylene, 300 mols of normal butane, and 930 mols of normal butylenes and extracted for removal of isobutylene which is recovered separately. The extracted stream consisting of 1240 mols of isobutane, 38 mols of isobutylene, 380 mols of normal butane. and 1255 mols of normal butylenes. This stream is solvent extracted with furfural or acetone to concentrate the normal butylenes and to remove a stream consisting substantially of iso and normal butane. The stream consisting substantially of isoand normal butane contains 1229 mols of isobutane, 12 mols of isobutylene, 337 mols of normal butane, and 255 mols of normal butylene and is withdrawn from the system for further use as desired whereas a total stream of 1080 mols is admixed with the butylenes recycle stream. This stream contains 1000 mols of normal butylene, 43 mols of normal butane, 26 mols of isobutylene, and 11 mols of isobutane and combined with the eflluent stream from the first isobutylene extraction zone and with the portion from the butadiene extraction zone comprises the feed to the butylenes furnace and to the butylene dehydrogenation zone. It will be noted that a slight discrepancy exists in the number of mols of feed stock charged and the components of the several streams making up the charge. It

will be realized that it is exceedingly difilcult toobtain a dynamic equilibrium on such an involved process, but the relative figures will serve to 11- lustrate the yields to be expected when proceedin: in accordance with my invention.

I concentration of normal butylenes.

In the foregoing example. where mention 0 mols is made, it will be understood that these values are pound mols.

The purpose of dividing the stream withdrawn from the butadiene extraction zone is to provide purge to prevent buildup of isobutylene in the system and also to allow withdrawal of the isobutylene as a desired product. The purpose of dividing the isobutylene stream which is being extracted is to prevent buildup of normal butane in the system and also to provide facilities for Also, the reason for subjecting the effluent stream from one of the isobutylene extraction zones to distillation to remove esters is to prevent buildup of these compounds in the stream recycled.

While the fractionation zone is shown intermediate the quenching and recoveryzone and the butadiene extraction zone, alternatively it may be desirable to install this fractionator or an additional fractionator in the recycle stream II or subsequent to the butadiene extraction zone, such alternatives fall within the purview of my invention. It will be apparent to the skilled worker that numerous modifications of my invention are a possible, and I intend to include such modifications within the scope of my invention.

The nature and objects of the, present invention having been completely described and illustrated, what I wish to claim as new and useful and to secure by Letters Patent is:

1. A method for dehydrogenating hydrocarbons susceptible to dehydrogenation which comprises forming a first feed consisting substantially of isoparaflin, admixing said first feed with steam, heating the admixture to a temperature in the range from 1000 to 1300 F. to cause dehydrogenation of said isoparafiin, forming a second feed consisting substantially of normal monoolefins, heating said second feed to a temperature in the range between 900 to 1200 F'., admixing the heated admixture and said' heated second feed to form a third feed, contacting said third feed with a dehydrogenation catalyst resistant to deactivation by steam to cause dehydrogenation of the normal mono-olefin components of said third feed, removing product including said dehydrogenated components and unreacted feeds from contact with said catalyst, and recovering said product.

2. A method for dehydrogenating hydrocarbons which comprises forming a first feed consisting substantially of isobutane, admixing said first feed with steam, heating the admixture to a temperature in the range between 1000 and 1300 F. to cause dehydrogenation of said isobutane, forming a second feed consisting substantially of normal butylenes, heating said second feed to a temperature in the range between 900 and 1200 F., admixing the heated admixture and said heated second stream to form a third feed, contacting said heated third feed with a dehydrogenation catalyst resistant to deactivation with steam to cause dehydrogenation of said normal butylenes to form a product including isobutylene and butadiene and unreacted hydrocarbons, removing said product from contact with said catalyst, and separately recovering said butadiene and said isobutylene from the product.

3. A method for dehydrogenating hydrocarbons which comprises admixing an isoparamn with steam to form a first feed mixture, heating said first feed mixture to a temperature in the range from 1000 to 1300 F. to cause dehydrogenation of said isoparafiin, heating a normal mono-olefin to a temperature in the range between 900 and 1200 F., admixing the heated first stream with said heated normal mono-olefin to form a second stream, contacting said second stream with a catalyst resistant to deactivation with steam to cause dehydrogenation of said normal monoolefln components of said second feed and to form a product including said dehydrogenated components and unreacted hydrocarbons, removing product from contact with said catalyst. substantially reducing the temperature of said dehydrogenated product to prevent reaction among the hydrocarbons in said product, and recovering said product.

4. A method in accordance with claim 3 in which the isoparaflin is isobutane and the normal mono-olefin is normal butylene.

5. A method for dehydrogenating hydrocarbons which comprises admixing steam with isobutane to form a first feed, heating said first feed to a temperature in the range between 1000 and 1300 F. to cause dehydrogenation of said isobutane, heating a stream of normal butylenes feed stock to a temperatur in the range between 900 and 1200" F., admixing said first feed with the heated butylenes stream to form a second teed, contacting said second feed with a dehydrogenation catalyst consisting of a major amount of magnesium oxide and minor amounts 01' iron oxide, potassium oxide, and copper oxide to cause dehydrogenation of said normal butylene and to form a product including said dehydrogenated hydrocarbons and unreacted hydrocarbons. removing product irom contact with said catalyst, substantially reducing the temperature of said product to a temperature suflicient to prevent side reactions among said hydrocarbons, separating the product into a first stream including substantially saturated components and into a second stream consisting substantially of unsaturated components, withdrawing said first stream and i0 returning it for admixture with said first feed, contacting said second stream with a first reagent selective for removal of butadiene from said second stream, recovering butadiene from said first reagent consisting substantially of normal butylenes, dividing said third stream into fourth and fifth streams, recycling said fourth stream as normal butylenes feed stock, dividing said fifth stream into sixth and seventh streams, contacting said sixth stream with a second reagent selective for removal of isobutylene therefrom, admixing said seventh stream with a mixture of hydrocarbons consisting of isobutane, isobutylene, normal butane, and normal butylenes, contacting said admixture with said reagent selective for removal of isobutylene therefrom, separately recovering said isobutylene from said second reagent and removing from contact with said second reagent an eighth stream from which isobutylene has been removed, contacting said substantially isobutylene-free eighth stream with a third reagent selective for removal of normal butylenes therefrom, withdrawing a substantially butane stream from contact with said third reagent selective for normal butylenes, recovering a substantially normal butylenes stream from said third reagent, and admixing said substantially normal butylenes stream with said fourth stream.

IKE D. HALL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,363,824 Wolk Nov. 28, 1944 2,376,323 Boatright et al. May 22, 1945 2,391,646 Schulze et a1 Dec. 25, 1945 2,414,816 Kleiber et ai Jan. 28, 1947 2,414,962 Mattox Jan. 28, 1947 

1. A METHOD FOR DEHYDROGENATING HYDROCARBONS SUSCEPTIBLE TO DEHYDROGENATION WHICH COMPRISES FORMING A FIRST FEED CONSISTING SUBSTANTIALLY OF ISOPARAFFIN, ADMIXING SAID FIRST FEED WITH STEAM, HEATING THE ADMIXTURE TO A TEMPERATURE IN THE RANGE FROM 1000* TO 1300*F. TO CAUSE DEHYDROGENATION OF SAID ISOPARAFFIN, FORMING A SECOND FEED CONSISTING SUBSTANTIALLY OF NORMAL MONOOLEFINS, HEATING SAID SECOND FEED TO A TEMPERATURE IN THE RANGE BETWEEN 900* TO 1200*F., ADMIXING THE HEATED ADMIXTURE AND SAID HEATED SECOND FEED TO FORM A THIRD FEED, CONTACTING SAID THIRD FEED WITH A DEHYDROGENATION CATALYST RESISTANT TO DEACTIVATION BY STEAM TO CAUSE DEHYDROGENATION OF THE NORMAL MONO-OLEFIN COMPONENTS OF SAID THIRD FEED, REMOVING PRODUCT INCLUDING SAID DEHYDROGENATED COMPONENTS AND UNREACTED FEEDS FROM CONTACT WITH SAID CATALYST, AND RECOVERING SAID PRODUCT. 